Speed governing mechanism for metal spray guns of the wire feed type



Aug. 14,1945.

A. P. SHEPARD AL 2,381,932 SPEED GOVERNING MECHANISM METAL SPRAY GUNS OF THE W FEED TYPE Filed Dec. 1941 6 Sheets-Sheet 1 INVEN TORS Ari/zurBS/zepard flerbertfflzylmm Aug. 14,1945. A. P. SHEPARD ETAL SPEED GOVERNING. MECHANISM FOR METAL SPRAY GUNS OF THE WIRE FEED TYPE Filed Dec. 1, 1941 s Sheets-Sheet z 1W a 1 X x N N M N 1%:

Q Q M $3 N 3 N M ,i i kw I I N M 0 0\ m m N Q N I 0 N "9 "9 o L\ b n 5 b w 1} [:11 o

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i i re *1 3 i INVENTORS: Arthur PJhepai'd Herbert .5! Ingham AT TOhN E'YD' P. SHEPARD ETAL 2,381,932 SPEED GOVERNING MECHANISM-FOR METAL SPRAY 6 Sheets-Sheet 3 GUNS .OF THE WIRE FEED TYPE Filed Dec'. 1, 1941 INVENTORS: Ari/nu P 15kt? 1erbrl 5.171 1am ATTORNEY 1945- A. P. SHEPARD EI'AL 238L SPEED GOVERNING MECHANISM FOR METAL SPRAY GUNS OF THE WIRE FEED TYPE Filed Dec. 1, 1941 6 Sheets-Sheet 4 mvsvroksz Ari/Jul P Shepard M. HerZeI-t 5 [fig/tam ATTORNEY.

/////7A/ mm wl annual IIIIIIIIIIIIIIII A. P. SHEPARD EIAL I SPEED GOVERNING MECHANISM FOR METAL SPRAY GUNS OF THE WIRE FEED TYPE Filed Dec. 1,

s sheets-sheet 5 IIIIIIIIIII/ I p j: 1-

e f' v .53- 1 56 35 7 IN NTO R5 Arthur Shepard I gel-bed .S. frgglzam ATTORNEY Aug; 4, 1945. A. P. SHEPARD ET AL 2,381,932

SPEED GOVERNING MECHANISM FOR METAL SPRAY GUNS OF THE WIRE FEED TYPE Filed Dec. 1, 1941 6 Sheets-Sheet 6 P l i l Q R. siaa a aq zy Myra;

'A'ITORNEY.

Patented Aug. 14, 1945 FEED TYPE" SPEED OVERNIN MECHANISM FOR' I METAL SPRAY GUNS OF THE WIRE Arthur P. Shepard, Forest Hills, and Herbert S.

Ingham, Flushing, N. Y., assignors to Metallizing Engineering Company, Inc., Long Island City, N. Y., a corporation of New Jersey 23 Claims.

This invention relates to new and usefulimprovements in metal spray guns of the wire feed yp Metal spray guns of the wire feed type are devices in which a metal rod or wire is continuously fed into a melting zone, fromwhich zone the metal is propelled in finely subdivided form by suitable means such as-a-bl'ast of air or other gas. The rod or Wire is fed into the melting zone by suitable rod. or wire ieeding means, such as knurled burs pressing against opposite sides of the wire. These wire or rod feeding means are driven, preferably operating through reduction gears, by a compressed-gas motor, 1'. e., a motor, he reiernf. w ichzi -r ta bsn the, iorce of com pressed gas. The load on the motor varies fro-m time to time due to the changes in the position of the'operatom-kinks 111': the Wire, etc. Since it is essential for successful spraying operations that the ratio of feed of the wire be uniformly main tained, it is likewise 'essentialthat the motor have a; comparatively stable speed of, operation, i. e., that itssp'eed of'operation befaffected'as little as possible variationsin th 'lo ad. One common 'ssed gas motof 'is a compressed gas In the operation of m essary to maintain different rates of feed when spraying different metals. For example, low melting point metals may be fed and sprayed more rapidly .than'higher meltingpoint metals and larger diameter wires must be fed and sprayed ere aslowl i h n; sma e ia r W e o he erb ma erie 1151 f the proper conditions. for th particoeb s ra edt P v in r placeabl gearing designed to permit the gun to begoperated at thesrequir ed rate of wire feed and topermit the turbine to z'opera'tewithin a range ofisteb wperat Chan in th e w- 'ever, involvesglloss oftim andthe possibility that v metal particles will be pig heel up by the gears in handling and interfere th the operation of the gun. When attemptiri'g to eliminategear changes by reducing the turbine speed through a throttling of the blastgas s'upply, the turbine becomes unstable and v a u niform wirefeedis no longer main-U tain'e'd as'the'th'en available power is insufficient to compensate for loadincreases.

ra i i aW iYi L t wine y lra id lie t m h -Nannies bine, however, necessitate the feeding application December1,1941, Serial No. 421,195

blast operated turbine 1i very susceptible to variations in the operating load. The ordinary gasturbine has sufiicient power for feeding the wire under normal condi-v tions as long as a sufiicient quantity .offgas is supplied to the turbine rotor at a sufiiciently high pressure; The power requirements of the turthereto of sufficient impelling gas to cause the turbine to operate at a very high speed. At 'whateverspeed, however, the turbine-operates with a given inflow and pressure of gas, allthei power is used up .and no excess power isavailabletotake care of variations'inthe operating load:

The governing mechanism in accordance with the invention is variably adjustable to, procuredifierent operating speedsandyet'is capable at any given speed to make excess power practically instantaneously available when required by-sud-.

den overload.

Our governing mechanism broadly cor'nprises at least one f rst-and one "second element substantially facing each other, one rotatable with the rotor of the compressed'gaszmotor, said first element being n'l'ovably mounted for operative actuation by suitable centrifugal speed. responsive means to frictionally' bear against'the other to thereby absorb power, and means for variably.

adjusting the relative position between said second element and. the initial position of said first element within a range of movement of the first element defined by the operating positions of said speed responsive means between minimum and maximum operatingjspeedsof said rotor.

In general, the selection of any particular centrifugal speed responsive device or the particular construction thereof depends, inter alia, upon consideration of. design,.practicability, desired accuracy and sensitivity, intended capacity of the metal spray gun etc., but foremost upon the speed rangerwithin. which such gun-is to operate. The

., latter, factor is- ,oruimportance as many metal spray uns of the hereinmentioned type normally operate withinaspeed-range where the maximumv operating'speedis in excess of 200% of theminim-umoperatin'g spe'ed;

' Withinthe preferred. embodiment of our inverttion, therefore; cognizance is'taken' of the fact governed over a Wide range of operating speeds. For instance, the speed range for the active operation of one particular gun of this type may be from 6,000 revolutions per minute (100 R. P. S.) to almost' 40,000 revolutions per minute (666. R. P. S.). This is a speed'increase from lowest to highest usable speed of over 500%. With any governor utilizing centrifugal force, this condition presents a particularly acute. problem because of the fact that centrifugalcfor ce varies as the square of the rotating speed. This means that if the ordinary centrifugal governor were added to the rotor of a metallizing gun; which operates through a 6 times speed range; the force operating on the governor weights would vary 36 times from lowest to highest speed and a mechanical movement actuating the=governori mechanism.

would be subject to equally great variations so that it is in such case practically impossible to obtain the necessary sensitivity at each and every speed. throughout the range. In a specific case,

for instance, if. the total movement of the governing mechanism; which. controls the speed, is

.150 between lowest and highest operating speedv of the" gun and if, a change from low speed to one tenth higher speed. produces a movement of .075" of the governing. mechanism thenv the remainin nine tenths of thespeedrange could. only actuate proximately proportional to the change in. speedv of. the rotor. throughout the speed. range covered.

by the governor.

The principle underlying the preferred construction ofthecentrifugal speed responsivemechanism in accordance with the invention will. be mores-fully understood from the following diagrammatic representation andderivation developing governor weight. positions for given speeds of rotation andibalanced-by. appropriate spring resistance: at such. positions.

x w y p In the: diagram, Y is the axis of rotation. of a governor element having an arm of the length l and carrying at-its'endthe mass M and pivotally connected at X. R is the distance of M from the axis of rotation Y, and o the angle of deflection. of the arm 1 from the axis of rotation Y.

When the governor element rotates at an angular velocity to about its axis Y, centrifugal force acts on the mass M in. a direction. perpendicular to theaxis Y. This force is indicated by the vector arrow-F. The. force F can be considered to be resolvedaintoa. component force indicated by the. vector arrow C, perpendicular to the arm I, and a component force indicated by the vector arrow S, in the direction of the arm I. The component force C tends to deflect the arm and, assuming the latter to move outwardly against a spring resistance, indicated by the vector arrow P, is balanced by the spring: resistance P at any given operating position of Z. Thisspring resistance P is defined by K in which K is'the unit spring force in dynes for unit angular deflection of l, i. e., for each. degree of deflection of I, through a, givenrange of deflection or corresponding valueof 4:.

T is the time required for one revolution and may be expressed in R. P: S.

w=21rR.P.S.

R=Z sin (5) F= Mums sin a a 0=F cos a (7 C=M41r m. l sin. 5 cos (8) 2 sin cos =sin 2 4; (9)

e=M21fiifsi l sin- 2 10 As C is balanced by the spring resistance of arm Z.

K= M21r R.P.S. l sin. 2. a 11. assumingl=1 and m=l 'K =21rR.P.s.' sin 2 12 may be expressed in radians or degrees if K is appropriately chosen) 7 Assuming as a representative" example an operating. range of from 6,000 to 40,000 R. P. M. (100 to 666 R; P; S;)' and a. total maximum deflection of 88 at amaximum speed of 666 R. P. S.,,

the value of K for equilibrium at that deflection may be found by inserting the various values in Equation 12 resolved for K.

21r R.P.S. 81112 21 6 sin- 176 Having established the unit value K for each degree of deflection through a range from 0 to 88 with a maximum of 666 R. P; S. at8 8, Equation 12 may be resolved for the detennlnation of R. P. S. for-different deflections of Z or values of i The R. P. S. values obtained for different values of are listedin the following TableI. Table I [Deflection range 09-88") a -010 20 .30 40 50' 60 so. as as R. P'. S. 0 118 118.02 124.63 134. 8 468. l 666 150. slim. 1 :20; 8 33111" Whenplotting the curve defined by Equation 12 in accordance with the values given in Table I the Z'curvehas in l igt lfltj in. When using spring force acting throughout; the entire range of to 88, an arm controlled by a spring force acting through a range beginning with a prede-' termined initial position at the angle 7 of the arm Z'with're'spect to the axis of rotation Y, a different value" for K controls. This value is defined by Equation 13 except that the value for t: (88

The 3.9. s values in a c rdance with'Equation 14 for predetermined angles or v are determined by I V I: I I 212 sin I (15) The R. PI s. v'ams for different vanes of and for eachseries. with constant predeterminedvalues for y and corresponding constant values for K are in the followi'ng Tables II, III, IV, V,

5 Table II [Deflection range to 88] I v "41' 50 J to 70 80 85 as R."1 .s 0 has 91.3 137.7 195.7 309.8 461.2 666 "Table III {Deflection range'yto 88] Y :50 Q 1 v 50 51 50 vo soljss es R. P. S 0 32.56 109.41 hasaoas" 461.2566

xTabZe IV 3 [Deflection range 'y'to 88] "60 61" 70 .80 s5 .88 0 40.711419 286.8 450.0 see w [Deflect ion range to 88] nf-7 9.? 5 l 1 70 71} .75 80 e5 88 0 596 i47.9"252.9 434.8 ees -j'rabze-vz, [Deflection range 7 to 88] 75 37s so s5 88 erer. 80.3 210.5 .4177 etc Th'e curves plotted for each series of values for' and R-P S5, given in-theforegoingtables, are.

instead of i an controlled by a:

a slope as demonstrated by curve I:

, mate fa constant all the way between minimurnoperating R. P. S. of 100 and the maximum opv illustrated in Fig.1? as II, III,IV, V, and VI corresponding respectively to the tables ofthe same.

designation. 1 1 Analyzing these curves, it willbe seen that in each curve there is av section or sections the slope of whichroughly approximates a constant, i."e., forapproximately equal increments in R. R S. there are approximately uniform increments in angular deflection of the arm I. This permits the speed governing mechanism to .be variably ad justed .to any desired R. P. S.-throughout the V R. P. S. range defined by the particular constant slope curve section and to thereby attain anapproximately accurate, uniform and sensitive speed governing operation. 7 y g It will be seen however that the different constant. slope curve sections of the various curves differ in the R. P. S. range covered by such curve section. Thus, for instance, the'section of curve I between. 10 and 70 angular defiectidmthough roughly approximating a constant in its slope, hasv a very steep pitch with respectto the abscissa and coversfor a total of 60 deflection an R .P. 8..

flection the pitch with respect to the abscissao f thes e secti ons is not as steep. As tothe section;

between '70" and angulardeflection off curve I,

there is an R. P. 8. range of 220 to about 46.5. 1. e. a totalR. P. S rangeof only 245 R. P. S. fora total deflection of 15 With respect to the section of curve Ibetween 80f and 88 angular de flection, the R. P. S. range is from 330 to 66or a total of only 333 R. P. S. for 8f deflection.

- It is thus seen: from the analysis. of curve I that there is no single constant slope sectionin this curve defining anywhere .an-R. P. S. range covering in excess vof 200% speed variations;

Though a governor element operating within the range defined by curve I may be .usedwithin the limitations inherent therein, .said governor element is ordinarily not satisfactory in the case of a metal spray gun of the wire feed type-nor mally operating within a speed range Where. the maximum operating range; isv in excess of: 200% of'the minimum operating range.

The dotted outlines of the various curves represent the plotted slopesbelow minimllm operating-R. P. S i. e., R. P. S. for'the device exem plified in this illustration. 7 Analyzingthe curves based on III, IV, V,and;VI) itwill be seen that curves II and. III do notpossess any section above mini slope roughly. approximates a constant and which.

definesanR. P. S. range covering inexcess of 200% speed variation. In curves IV, V, and VI, it will be seen that these curves roughly approxierating RIP. S, of 666f which is equivalent to an R. P. S. range'covering. in excess of 500%;speed variation. In these cases the approximation "of a constant increases with the increase in the predetermined initial angular 'positiono'f the arm with respect to the'axis of rotation, and, although for practical operation apredetermined angle of 60, as exemplified by curve IV, will give satisfactory results, higher angles-as illustrated by curves V arid VI-are preferred. Althoughthe constancy of the slope improves with higher initial angles; it has been. found. that the. governing element a predetermined initial angular position of, the arm 1 (curves II,;

position between 'w and 80 and preferably'i'at approximately 75 with respect to itsnaxis: of 110-.- tationt is preferred. This is; exemplifiedc-inits" operating range by curve VI- Initial position?" or similar expression as used hereininconnec tionwith the armor arms in accordance with.

our-invention is intended toconnote the angular position assumed by the arm or arms at. zero speed. Y

Although in theforegoing equationsand the various. curves illustrated in Fig.1? a. minimum" operating range of 100 R. P. 'S. and a maxi-mum" operating rangeof 666 B. P. S. with an assumed maximum deflection of 88 have been selected, it

i's unders'tood that these values are merely used by way of exemplificati'on of the principles underlyih'g the preferred embodiment of our invention; The results are not substantially difierent and the same type of curves result if other values or ranges are substituted forthose hereinabove-- The above derivation shows a relationship between governor "weight positions and speed at whichequal increments in speed produce approximatelyequal increments in" angular posi-- tions of the governor arm. It is now possible to combine a lever arm and weight structure;

embodying this principle, with speedcontrol means and with'means for adjustably positioning "such speedcontrol means to produce a governor operating satisfactorily over a wide speed range:

In the actuar operation ofthe governor there is ,a governing force acting to control the speed and in the illustrations shown inthe drawings,

thisgoverning force is parallel to the axis of ro-- tation. For a complete analysis of the forces in' volved during governing, this governing force must be taken into account, as well as the centrifugal'force and spring force. This governing force, however; neednot be considered in developing the 7 relationship between governor weight positions and speeelat which equal in crements in speed produce approximately equal increments in angular positions of the governor arm: r

*The variable "speed governing mechanism," in

accordance with the preferred construction of the invention, for a metal spray gun of-the wirefeed type, having compressed gasmotor, comprises atleastone arm; rotatable withtherotor of suchmotor' and centrifugally defl'ectable for angular deflection with respect to its axis of rotation, against spring resistance, from a predetermined initial position and preferably from a predeter' mined initial position of at least 60 with respect to such axis speed-control means, composed of means for variably adjusting the relative position between the second element and the initial position. 01 the first. element within a range of mechanical movement of the first element defined by .the angular deflection of the arm or arms.

between minimum and maximum operating speedsof the rotor. The initial position of the first. element. of the speed control meansrreferredwith: toohigh a predetermined initial angle'ma'y losesensitivity. For'best results an armlhavingr its spring set for a predetermined initiahangul'ar.

to herein, designates that position of.-jsuchfirst element as is controlled by the defiectableaarm or arms at its-or their initial position; 1 a 1.

The metal spraygun of the wire feed. type embodyi'ng our invention. does not require any change of gearing; The same is capable of maintaining' any numberbf practical wire feeding' speeds and: may beshifted fromone speed togan other by. a simple adjustment-of thetpreferably manual. control means. Furthermore, the-motor or turbine of such metal spray gun is at all times maintained in astable operating condition. The particular construction in accordance with the preferred embodiment ofour invention permits J the use of these metal spray gunsninder substam.

tially stable operating conditions, over a much wider range of wire feed speeds than is otherwise possible.

The invention will be more fully understood and further objects thereof will appear from the following description read in conjunction with the drawings in which:

Fig. 1' is a side view of'the rnet'al lsprayfgun il lustratin'g one embodiment of a'construction in- Fig. 4 is a vertical section through the c on struction shown in Fig. 1. on the plane indicated- Fig. 5 is a vertical section through the construction shown in Fig. 1 on the plane indicated by V-V except for the construction offthe structure illustrated in Fig. '7 whichis shown on the plane indicated by the section line V'V in Fig. "I;

Fig. 6 illustrates a shown in Fig. 5;

Fig. 6A is a plane view of the interior of the construction shown in Fig. 6;

Fig. 6B is a view'of one element of the construction shown in Fig. 5

Fig. 7 is a side view of the rotor element of the spray gun; 1

Fig. 8 is a View of part of the construction shown in Fig. '7 at right angles thereto; I

Fig. 9 is a, central vertical section parallel to view of part of the section the construction shown in Fig. 1; u

Fig. 10, is a vertical section through the constructiomshownin Fig. 5 on the plane indicated y X-Xi i a -Fig..1:1 is a sectional view of Fig. 5 in the plane 7 indicated by XIXI;

struction shown in Fig. 5 on the plane indicated by XIII-XIII;

Figs. 14,15, and 16 illustrate sectional views of variations in the construction of a spray gun embodying our invention.

Fig. 17 is a graphic representation of the principle underlying the preferred embodiment of the invention.

The centrifugally actuable arm element in'accordancewith. our preferred structure may be 1 any one or a multiple number of suitable spring force controlled arm or arms; we prefer a construction, however,.where the armelementis a spring element such as for instance one or more spring arms, i. e., arms. made; of spring; material, set at the desired predetermined? initial-angle.

satisfactory deflection. I

- .Inicase of a substantially rigid arm, we prefer tation. When using one or more spring arms,

.pivotable mounting thereof may be dispensed with as a rules'ince these as such will usually permit Referringto the drawings I'(Fig. 2) indicates the inlet for oxygen or other combustion supporting. gas, 2 the inlet for acetylene or other combustible-gas, and 3 the inlet for .air'or other gas for atomization of the metal, projection of the metal spray and driving turbine. When plug '4 ofvalve 5 is in the position shown, each of the inlet registers with a corresponding hole in the plug, these holes being indicated by numerals 5, 6 and I respectively. In this position. oxygen flows through duct I2 to mix with the oxygen in duct Hand the air flows throughduct I5' into chamber I6 and also through the side connection turned from the offpositio-n, which is at a. right 'angleto the showing in Fig. 2, first some comspeed. Alternatively, all the valve'passages may be opened but" at such rates of flow as to establish favorable lighting conditions which are different from the conditions obtaining when the fines a hole 2| of rectangular cross-section which fits closely the shank 22 (or corresponding section) (Fig. 2) of the plug 4. The washer 20 is formed with the depression 23 (Fig. 3). This washer is spring pressed and this depression 'II into turbine manifold l9. Openings 5, 6 and "I in 'plug 4 are so arranged that as handle 8 is gun is in operation. The washer 20 '(Fig. 3) de- ,air tip 4| and conical exterior of burner tip 34 may be adjusted with corresponding variationsin the characteristics of theair blast. When a satisfactory adjustment has been made, the top 4| is locked in position bythe lock nut 44. It will be noted that the air "in passing forward from the chamber IB goes through the constricted annular space 45 which exerts a definite control over the volume of air passing. As a result of this construction and the orifice effect thereby created, the-adjustment of-air tip 4| modifies the characteristics fthe air blast without so great a modification of vthe volume of air passing thereto as would otherwise result, which is decidedly adyantageous in the adjustment and operation of the gun. I The wire-3l (Fig; 9) enters the gun through the annular guide 50 of hardened material in which is the duct 5|. The upper and lower surfaces of the wire are engaged respectively by the burs Hand 53. Bur 53 is carried-by shaft 54, which shift is driven by'an air turbine through suitable intermediate gearing which will be'hereinafter described. Shaft 54 (Fig. 4) alsodrives the gear 55 in mesh with gear 56, which in turn drives the upper'bur 52. Both gear'50 and bur 52 are secured to the tubular member 51 which rotates on the spool 58 carried by pin 59' (Fig. 4) The screw 59 is carried by the saddle '60 and this saddle is pivotally secured (Fig. 9') to frame 6| 'of the gun by the hinge'BZ. When cap 65 is turned the thread member 68 which is a partof frame 6 I. and thespring I0 exerts pressure on the saddle .60, thereby forcing the upper bur 52 toward the lower bur 53 and thereby causing the burs to engage and advance the wire 31. Conversely, when cap 65 is turnedin the reverse direction, pressure slips onto the head of pin 24 when handle Bis in the correct position for lighting the'burner.

This offers sufiicient resistance to'indicate to the operator the lighting position. After the burner has been lighted a slight pressure against handle 8 forces the depression 23 out of engagement with the header the 'pin 24. A further movement of handle 8 causesoxygen to flow through duct I0 which establishes a a melting flame with the ignited gas and the final movement of handle 8 to the position shown in Fig.2 permits air to flow into duct I5 and thence into chamber I6 to project the sprayed metal upon the surface to be covered.

The construction of that part. of the gun by which the rod or wire is melted and projected will be explained by reference to Fig. 9. The wire moves forward to guide 3| and through duct 32 to the interior 33of the burner tip 34. The mixture of air and oxygen moves forward through the ductI I, which is immediately behind duct.32 (the arrangement is shown in Fig. 2) and into the annular space 35. From this annular space 35 the. combustible mixture moves forward through a number of holes to be discharged through convergent orifices 36-against the wire. This forms a zone of gases undergoing combustion, whereby 'the' chamber' I6 advances through the annular spaceisurrounding burner tip 34 and is projected by air nozzle 4| in such a way as to sub-:divide and propel the molten metal. Thea'ir -tip*4I' is threaded to the outer shell 42 of the burnerso that. the orifice 43 defined by conical-interior of of spring"! on saddle 60 is released and the burs move freely withoutengaging and advancing the Wire. I I

The shaft 54 (Fig. 4)"which drives burs-53 is mounted in ball-bearings I0 and 'II. Bearing-I0 is held in frame BI and bearing II is heldin the housing 12 which is attached to frame 6I.- The shaft 54 is driven by the worm gear 13, which in turn is driven by the worm I4, carried by the shaft '15. Shaft 15 '(Fig. 10) is carried by ball-bearings I6 and 'I! mounted in the housing I2. Shaft :15

is in turn driven through-the 'worm gear I8 by ing I00 are apparent from Figs. '7 and 8. As evident from Fig. 6, cover includes the mounting IllI for the ball-bearing 86 and three ridges I02 (Figs. 6 and 6A) radially arranged" about mounting IN on the interior surface of the cover. The washer-shaped member I03 is made of 'fi'ne wire'mesh and rests directly upon ridges I02. The washer I04 rests'directly on the washer I03; The

washer I04 defines the perforations I05 (Fig. 6A). The washers I03 and I04 are held in contactwith eachother and with the ridges 102 by the strips I00, which in turn are secured to the ridges I02 by the screws I0'I.' One result of this construction is that the exhaust from the turbine flows through perforations I05 in the washer I04, thence through openings in the fine screen of which washer I. I03 is composed, and' thence through exhaust ports I I0, in cover-30 (Fig; 6 and .202 with ears 209 of spring clip 20.1.

Fig. 1) thereby resulting in more quiet operation -of the turbine. i Y

i i The nozzle arrangement operating the turbine "is shown in'Fig. 11. Face H5 together with the housing ell-defines the space in which the turbine drum rotates; (the .drum is not shown to facilitate inspection of the nozzle structure). A nozzle I in accordance with the invention, rotor 95 carries '3 governor in spring element 200 mounted thereon bymeans of screws 20l. This spring element is setwith respect to theaxis of shaft 80 at an angle of approximately The weights 202 'in this "case consist of screws clamped through a hole in eachend-of the spring 200 by the nuts 203.

"-When the rotor 95 is at rest, the weights 202 take the'position" show-n. When the rotor 95 rotates, the centrifugal force acting on the weights 202 tends to pull them away from the axis of the shaft and iniso doing tends to deflect the arms of the spring 200 forwardly towards a perpendicular position to the axis of shaft 80. This tendency of the springs to straighten under the centrifugal forceQa'cting on the weights is increased by the weight of nuts 203, which, because they extend beyond the 'bent spring exert 'a twisting force due to the action of centrifugal force whichtwisting forceis also in the direction to deflect the spring arms 200 nearly perpendicular to theaxis of shaft '80. When the rotor 05 is operating at the lower end of its speed range, the spring arms 200 are but slightly deflected from their initial position. In this speed range a slight :change of speed causes a motion of the buttons or 'weights essentially in the direction of axis of shaft '80, due to the change in the amount of centrifugal force acting on weights 202 and nuts 2-03. The deflection of the spring is not proportional to the square of the speed of rotation. As

the Speed increases and "the buttons 202 move approximately parallel to. the axis of shaft '80, they deflect the spring arms '200 to a position more nearly perpendicular to the axis of shaft -80. The buttons 2.02 therefore operate in and out essentially parallel to the axis of shaft throughout the entire large speed range required for a metallizingng'un, and the position of the buttons 202 at lany speed represents a measure of that speed.

Slidably mounted on shaft 80 is brake disc subassembly 204. This sub-assembly consists of hub 205, disc 206gand bent clip 201. Bent clip 201 and disc 206 are mounted on hub .205 and secured thereto by screws 2:08. The ends of the arms of the piece '20! are bent up to form ears or prongs 209. As assembled these ea-rsn209 fit either side of each weight button 202, hence, as rotor 95 rotates, brake disc sub-assembly 1204 also rotates being driven by the contact of weight buttons Mounted on-shaft 80 next to bearing 86 is washer 210. NM 21 l which screws on to threaded end of shaft '80 clamps bearing86'and washer 2) against;

all)

the shoulder of the shaft 80. Assembled between washer 2H] and the hub 205 is the compression coil spring 2I2. This coil. spring 212. normally tends 'tohold the brake disc sub-assembly 204 towards the rotor 95, so that the weight huttons 202 contact the *ends of spring clip 20?.

111' operating, as the rotor 95 speeds up, the weight buttons202 mo've parallel tothe axis of shaft'80 towards theilorake disc sub-assembly 204, and by the contact of the buttons 202 with the spring clip .1201" force the brake disc sub-assembly .204 to slide alongtheshaft 80 iniopposition to the coil spring'Z I 2. Theturloine housing is;cut

away at three sections 213, so as to permit the three segmentsZ M of spider or -friction ring 2l5 .to fitdooselythrough the resultingopenings. The outer periphery of the three-segment 214, of .spider2l5 are threaded Ring nut 216, substantially forming an extension of the turbine housing 90, is threaded 'in its bore to engage the threads of spider2 l 5. This thread extends on the boreof ring nut 2|6 toa neck at the end of the thread which" is terminated by .shoulder 2H. When the nut 2 I5 is turned the spider 2 45 travels in andv out on the thread and is stopped at one end of its travel by shoulder 12 I1, and at the other end of :its travel by forcing brake disc sub assembly 204 to the limit of its travel towards the rotor; Rin nut 2L6 is rotatablymounted on housing 90 and is located :by bearing surface 218. Disc 2!!) is secured-to housing'90 .by screws 220, and'acts to restrain the ring :nu-t 2-16 on the housing 90 between the housing. shoulder '221 and itself so that the ringnut H6 is freeto rotate but cannot move longitudinally. Ring nut-2 I6 is provided-with groove q222 and 223, which extend around'itsfaces and which are packed with a packing material such as cork or graphite impregnated cotton string. This construction serves the double purpose of keeping dirt out of the mechanism and also of providing a necessary amount 'of friction so that-ring nut 2L6 will not turn accidentally. A-section of the outer periphery of ring'nut 2|6 is knurled at 224,;to provide an easy grip'to the fingers forturning. As that portion of the housing 90 which has not been cut away 'to allow space for the spider segments 204 straddles these segments of the spider 2l5, the spider 2l5-is not permitted to rotate, but is permitted to move parallel to the-axis of shaft 80. By screwing the ring nut. 2H3 one 'way or the other the spider 2 l 5 maybe located, longitudinally in :any desiredposition within the limits of its .motion. The ring shaped face 225 of spider 2.15 (Fig. 6B) represents a braking surface to contact the face of the brake disc 205. Brake disc 1206 is preferably made of hardened steel and polished on its contacting surface; The braking surface225 of "spider H5 is preferably-made of .sprayed metal, most preferably of sprayed bronze.

For smooth operation i-iti's important that the coefiicientof friction, between these two surfaces remainas constant'gas possible throughout varying conditions of service, as well as throughout vary- 'ing conditions'rof lubrication. :Sprayed metal is particularly adapted forthis purposebecause of its constant coefficient of friction and because due to its porosity it will absorblubricant and hence operate under atleast semi-lubricated conditions when it might :be otherwise operating dry. 1 The braking-face 225-.may be divided into segments if desired by cutting anumber of radial shallow slots 226. Such slots. 226 will tend to collect foreign matter and prevent scratching of the past' 'beariri'g' 86 and washer 210 and be thrown upwards by the-rotatingwasher H in such a di- 'recti'onthat some of the grease will locate on the 'th'reads' of ring nut 2I6 and'some of the grease will 'lo'cate onthe inner periphery of spider 215 and-find itsway' to the bearing surface 225. 'Hence', the whole governor mechanism'may be lubricated, 'aswellas the bearing 86 by the in- 'troduction-o'fgrease intochamber 229. 1

"-Bent clip 201 performs the double function, first "of providing "a driving means through the ears 209", the buttbns'202, thespring 200 andthe rotor SF'betwe'en -th'e' rotor'and the'brake disc suba's'se'mbly'20t "The other function isthat of absorbing 'byits resiliency the pounding ac'tionof V:

wightbuttons-202. When operating at high speeds; the'ie'is a natural tendency for the weight buttoi'i's-'202which are mounted on t'he ends of spring arms 200 to enter into a vibratory'motion.

Thisrnotioh'isquickly absorbed by the resiliency of thearr'ns' of bent clip 201. It will be understee thatflcfent' clip 201 may be eliminated from {the subf-ass jnibly 204 and thatthe weight buttons 202 may then be made to beardirectly against br'ake""disc 206." If b'ent clip 201 is eliminated, -1

however, some other means such aslreying, gearing,-"or'fother'drive connectio'n should be. used to "d "brake discsub assenibly 204 and cause it to 95. Whenbentclip 201 is weii d hthrwise be; possible, as j i .1201 'rve's to apply thrust load fromthe, weight Mfrnore 'nearlYat the center ofdisc "205i," hence "m'm1mizmg the distortion due to [an unevenlybpplieddoad;

1p oper'atien ring nu zl'efis tur e to locate *spitlerj2 I5 any desired j position corresponding to' a dsire "s'peedl' a' full volume of airunder run ress re is providedat all times to the turbine I -ro tor9'5';' thisrotor willtend to'increase its speed,

causin weight buttons 202 to 'move toward brake disc sub-assembly'204 and 'cause'the brake idisc 'sub assembly F to move 'tov'v ar'd the friction -surface '22'5 'of spider 2l5.". As thedesired speed isreached the brake disc 206 brushes against 'fricabsorbing any excess-power which maybe de- ""the brake d1sc 206 may be made l ghterrelease the pressure between the friction surfaces 206 and 225: As this pressure is released less 'friction occurs and less heat is generated and hence anextra amount of power is released for active-use of the turbine and driving mechanism, and hence no further reduction in speed occurs. On the other hand, if the-load "on the driving mechanism reduces suddenly oreven gradually, the rotor 95 tends to speed up very slightly. Even a slight increase in speed is sufiicient to cause this sub-assembly to press harder against the friction surface 225,..which results in a greater amount of power'being absorbed by friction; hence, only-a-very-slight increase in speedis possible even though the load on the driving mechanism would berr'el'ease'd entirely. Theaction of, the governor is practically instantaneous ,so that a very steady wire feed drive is provided, whichycan easily be adjusted to any given speed over a wide range of speeds by the simple expedient of turning ring nut 2G6. This constancy of wire feedisfimain'tained even with variations in the amount ofpressure'of the blast gas suppliedfor the-operation of the turbine. The construction shown'in Fig. 14 is similar to that described-above,except that brake disc subassembly 204 has been eliminated. In-this con struction Weight buttons-202' operate the same as previously described, except that as they move parallel to the axis of shaft under the action of centrifugal force; they are caused 'to contact directly with the friction fsur'face 225' of spider .2 l5, -With-this construction the friction surface :225"-is smooth and continuous and'is'not slotted as at.226'in the previously described construcntijonv Friction in this caseis procured directly between the action of -weight buttons 202 and friction surface 225- but the adjustments in op'- erationyare otherwisethesam'e as'previously described. 1

..In thev construction shown in Fig. 15 the rotor spring, and weight button construction and the .brake: disc subassembly construction are the s'ameyasthat described inconnectionwith Fig. 5. In this construction, however, the turbine housing. 9 0 isnot cut-away as at:2|'3 (Fig; 13) as no spiderlnor ring nutis used Instead, screw 23-! isprovided to operate through a threaded hole 232 in housing The outer end 'of screw 23! vis pro vided with a knurled knob 233 and at the ,inner'end with a smalldisc 234 which is faced 'ti'onsurf'ace' 225, generating heat by'l'frictionfthus veloped bythe turbine'rotof95. Any heat which I .isrthusdeveloped is absorbedand carrie d away bytheexh'aust 'gasfroni'the turbine" which must,

pass: zaroundzthe spider 2l5- before finally exhausting: through ports 1 l0: The speed of the rotor. is,':therefore, accurately established by the positionof the spider2 I 5, for if the rotor tends to travel faster, increased pressure-isexerted between brake discandbraking surface 225, causing anincrease in friction.':: If due toa kink or bend inwire 3! orasome'other cause'an increased .loadisimposed onthe drivingmechanisin of the metallizinggun, this load causes the rotor!!! to slowdown very slightly. .However, even-a very slight reduction in speed is sufficient to cause the weight buttons 202 -to moveislightly' away firemthe brake disc, sub assembly 2 04: arid hence 'wii hiriction material 235', preferably made of sprayed metal. The operation 'zis the same as that described inconnection with-=l fig.5 except that as the rotor, speeds up, brake disc isubassembly 204' .is forced to contact friction sure face 235 until sufficient friction is generated and absorbed to permit the turbine to arrive at'and maintain its pre determined speed. In this case, the speed is pre-determined or adjusted by the location of friction'surface 235 which is obtained by "screwing the screw 23| in or outby means of the knurled knob 2'33.

The construction shown in Fig. 16 is similar to the construction described in connection with Fig. except that brake disc assembly 204 (of 'Fig. 5) has been replaced by friction button subassembly: 236. This assembly consists of a hub 231, slidably mounted on shaft 80'" and. a bent cli -"23a 'similart'o' bent clip 201 f Fig. 5, which is secured to hub" 231 by screws 239. Ears 240 are provided at the ends of bent clip 238 for the same purpose' as describedin 'connection'with bent clip 201 of Fig." sw on each end of bent between minimum and maximum turbine to operate at a predetermined.speed. The

control and operation-of themechanism with this construction of Fig. 5, as :the friction button subassembly 236 replaces the "friction disc subassembly :204 of Fig. 5.

As aforementioned the speed governing mechvani-sm in accordance with the preferred embodiment of our invention broadly comprises a first friction element, capable of mechanicalrnovement induced by the operations of the arm or arms, and a second friction element, cooperating with the first friction element to effect any desired speed variablyxadjusta'ble within the entire speed range. Thus, for instance, referring to Fig. 5, brake disc 206 constitutes the first friction element operated by the movement of the' spring .arms 200 by way of :the buttons 202 and clip 20:1. The second friction element constitutes in this case the friction 'face'225 of spider 215 variably adjustable within the'range of mechanical movement of the brake disc 2ll6 a s controlled :bythe deflection of the spring arms 200 speeds of the rotor95.

Alternatively as seen in Fig. 14, thefirst friction element may be defined by the frictionbutton .20? operated by the deflection of the spring arms 200', the second friction element ing this case being the friction face 225" operating and variably adjustable similar to "the second element described'in connection with Fig. 5. Further modifications of first and second friction elements in construction and operation similar to those exemplified by Figs. 5 and 14 are illustrated in Figs. 15 and 16. H 7

Our invention is not limited to the construction of a spray gun illustrated in the foregoing example and may be used in connection with any other suitable gun constructions of the gas blast wire feed type, including those having other heating or melting means for the wire, such as .an are or the like and further including those .constructions of this type in which multiple wires are fed to the heating zone. a 7

'Although within the preferred embodiments exemplified in the foregoing figures the speed control mechanism is illustrated in connection witha motor of-the air turbine type, it is within the scope of our invention to use our novel. speed control construction to govern other types of compressed gas motors in wire feed type metal spray guns.

The present application broadly covers a speed governing mechanism having speed control means effecting Speed control of a rotor of a metal spray gun of the wire feed gas blast type by friction elements cooperating by mechanical movement and actuated by centrifugal means; our co-pending application Serial No. 421,194 covers a. speed governing mechanism having speed control means comprising speed control elements cooperating by mechanical movement and actuated by centrifugally operated'and angularly deflectable arms; and our co-pending application Serial No. 421,196 covers a speed gov erning mechanism having speed control means regulating the compressed gas supply to the turbine of such metal spray guns.

tor, first means rotatable with said rotor and comprising at least one arm centrifugally deflecti-ble with respect to its axis of rotation,

against spring resistance, from a predetermined initial angular pre-set position with respect to said axis-second means composed of at least one first andat least one second friction element, one of said first and said second friction elements being rotatable with said rotor and the other :mounted for braking action with said rotatable friction element upon frictional engagement therebetween, said first friction element being positioned and adapted to be operatively acted upon by said first means upon-centrifugal'actuation thereof for total mechanical movement defined by the centrifugal movement 'of said first means between minimum and maximum operating speeds of said rotor to frictionally bear against-said second frictionelement to thereby effect speed control of said rotor by power absorption, and means forvariably adjusting the relative position of distance between said second friction element and the initial position of said first friction element throughout the range of said total mechanical movement -of said first friction element.

a metal spray gun construction of. the wire feed type, having a compressed gas motor, comprising at least one arm, rotatable with the rotor of said motor and .centrifugally defiectable for angular deflection with respect to its axis of rotation, against spring resistance, from a predetermined initial position vof at least '60" with respect to said axis, speed control means-composed of at leastone first and at least one second friction element, one of said first and said second friction elements being rotatable with said rotor and the other mounted for braking action with said rotatable frictionv element upon frictional engagement therebetween, said first friction element being positioned :and adapted to be operatively acted upon by said arm upon centrifugal actuation thereof for total 'mecham'cal movement defined by angulardeflection of said arm between minimum and maximum operating speeds of said rotor to frictionally bear against said second friction element to thereby effect speed control of said rotor by power absorption,

and a separate mechanism for variably adjusting the relative positionof distance between said second friction element and the initial position of said first friction element throughoutthe range of said total mechanical movement of said first friction element.

3. A variable speed governing mechanism in accordance with claim 2 in which at least one of said friction elements defines, at least substantially on the path of frictional travel of the other friction element when in frictional contact, a friction surface substantially constituted of spray metal.

4. A variable speed governingmechanism for a metal spray gun construction of the wirefeed time having -a c 'empressed motor, comprising at'f-l east one armrotatable with the rotor of said mbtdr anu centrifugally deflectable -for angular .deflectio i with"resp'ect its axis of rotation;

a'g'ainst' 'spring" resistance;- from" a predetermined initial position of at'least 60,; with respect to said axis; speed control meansf composed of at least one first friction element and one second friction element said second? friction element being nlblillted fol" brakingaction with said first frictionelement upon frictional engagement therebetween, said firstfriction element being rotatable with said rotor andmoiinted for total mechanical movement deflned by angular deflece v tion of said arm between maximum and minimum operatin'g s'peeds or said rotor to contact said second friction element and for operative".

actuation by said-arm;upon centrifugal actua- 7 tion thereof to bear frictionally'sagainst said 'sec-" ond friction element to thereby'eifect speed controlof said rotor by'power'" absorption, and a separate l mechanism for varialcvly adjusting the relative position of distance between said second friction a element andthe initial position of first friction element throughoutthe range of said total mechanical movement.

v5. A: variable speed govermng"mechanism in accordance with claim 4, except that'said' arm is centrifugallydeflectable from a predetermined initial position of from 70 to 80'with respect to said axis. i

6. Avariable speed governing mechanism in accordance with c1aim;4, in which said arm carries-a weight adjacent the end thereof. p

I 7. A- variable speed governing mechanism j in accordance with claim4) in which said'flrst frictionelement is defined a fweight carried by saidarm adjacent the end thereof and inwhich' said second friction element is definedfby at least one frictionsurface alongsthe rotary path of travel of-saidweig'hti;

A :variable=--'speed' governing mechanism for a-metal" s'pray'gun construction of the wire feed type having a" compressed gas motor, comprising at least one arm carrying a weightadjacent the end thereof, said" arm being rotatable with 'the rotorofsaid motor and centrifugally deflectable for angulardeflectionwithrespect to its 'axis of rotation; against spring resistance, from'apredetermined initialpositionflof'atleast 60 with respect to said axis, speed], control means composed ofat least -one first riction element'and one: second friction element said? second friction element being mounted forbraking'action "with said first" friction element upon frictional engagemerit tl ierebetwe'en, said first friction vele ment being rotatable with said rotor and mounttype *having a compressed gas: motor, comprising at'l'eas t one' ar-m carrying 'a. weight adj acent" the end tliereoffi 'said arm be'ing rotatable with therotor of aw-matter and centrifugally-deflectable for angular deflection-"with respect to itsaxis of rotation against spring-resistance, from a predetermined initial osition-"or "at" least 60' with respect to" saidaxis, speed control means composed of 'at' least ioneii'first; friction'- element defining at least 'one first-friction surface rotatable with said; arm I and one second i friction element defining -at least onese'c'o'nd' substantially stationary-friction 'surface' aligned with the rotary path of: travel ofsaid first friction surface said second frictionsurface-being mounted for braking action w-ith' said first friction surface upon frictional engagement therebetween, saidiirst friction surface being slidably mounted substantially coaxialwith-:the-axisof rotation of said arm for :total mechanical; movement defined by angular deflection of said arm between maximum and minimum operating-speeds of said riotor to .contactsaid secon'd friction surface and for operativeactuation-by said arm upon centrifugal "actuation thereof to 1 bear 7 frictionally against said xsecond' friction surface to thereby effect speed control -of said rotor by power ab-' sorptionpand a separate mechanism for variably adjusting the relative position {of distance between saidsecondfrictionsurface and the initial positionaof said first frictionsurface throughout thelrange of:saidtotalmechanical movement.

11110; A bvariable .speed governing mechanism in accordance with c1aim-9 except 'that said arm is .centrifugallydeflectable from a predetermined initial position of from 70 to t0 with respect to edafor 'totalmechanical 'movement defined by angulandeflectio'n'of'said arm between maximum v and ;.minimum* operating speeds" of said rotor to contact said second-friction element and for oper'ative; actuation by isaid 'arm upon centrifugal actuation; thereof .to be'ar 1 frictionally against said second friction element to thereby efiect speed control by power absorption, at'least one resilient clip adapted and positioned to rotate with and bear against said' arm, and a separate mechanism for variably adjusting the relative position of distance vbetween said second friction element and the initial position of said first friction element throughoutthe range of said total mechanical movement; I

9. A variable speed governing mechanism for ,a metal spray gun construction of the wire feed 1,- 1 1. A l variable :speed governing mechanism for a metalsprays'gun construction of the wire feed ,type having .a compressed gas motor, comprising at-le'ast; one arm rotatable with the rotor. of said motor: and. 'centrif'ugally deflectable "for, angular deflection with respect to its axisof rotation, againstspring resistance. from a predetermined initialspositionof at least 60 with respect to said axis,r.a:first frictionsurface substantially coaxial with the axis of rotation of said arm, a second friction isurface, substantially c oa'x'ially rotatable with said am and s'lidably mounted intermediate said/arm and said first friction surface for operative actuation .by said arm; against the force of; a :spring and for total mechanical movement defined by the total" angular deflection of said arm= between maximum and minimum operating speeds of said rotor to 'frictionally' bear, upon centrifugal actuation of said arm, against said.

first friction surface; said'first friction surface being mounted for braking action with said secand 'friction surface up n frictional engagement therebetwe'en a'nd "at-separate mechanism for 

